Sunil Kumar, P. B. ; Ranganath, G. S. (1991) Geometrical theory of diffraction Pramana  Journal of Physics, 37 (6). pp. 457488. ISSN 03044289

PDF
 Publisher Version
4MB 
Official URL: http://www.ias.ac.in/j_archive/pramana/37/6/45748...
Related URL: http://dx.doi.org/10.1007/BF02846778
Abstract
Geometrical theory of diffraction (GTD) is an alternative model of diffraction propounded first by Thomas Young in 1802. GTD has a long history of nearly 150 years over which many eminent people enriched this model which has now become an accepted tool in the calculation of diffraction patterns. In the conventional HelmholtzKirchhoff theory the diffracted field is obtained by computing the net effect of the waves emitted by all points within the area of the aperture. But GTD reduces this problem to one of computing the net effect of waves from a few points on the boundary of the aperture or obstacle, thus simplifying considerably the labour involved in computations. Also the theory can easily be modified to include polarization effects. This has been done specifically by Keller (1962) who exploited the Sommerfeld solution of diffraction of electromagnetic waves at a half plane, making the theory more versatile than the Kirchhoff scalar wave theory. Interestingly the geometry of difffracted rays is predictable from a generalized Fermat principle. According to this the total path chosen by light from the source to the point of observation via the diffracting boundary is an extremum. Historically it should be stated that many of the salient features of GTD were established by a school led by Raman which was active from 19191945. Later when Keller (1962) revived GTD independently, he and others who followed him rediscovered many of the results of the Raman school. We have stressed wherever necessary the contributions of the Indian School. We have also discussed certain geometries where GTD can be effectively used. We get some new and interesting results, which can be easily understood on GTD, but are difficult to interpret on the conventional theory of diffraction.
Item Type:  Article 

Source:  Copyright of this article belongs to Indian Academy of Sciences. 
Keywords:  Diffraction; Fresnel Diffraction; Boundary Waves 
ID Code:  93216 
Deposited On:  14 Jun 2012 12:42 
Last Modified:  19 May 2016 06:21 
Repository Staff Only: item control page